A tractor scraper is a type of earthmoving equipment used to perform a variety of operations, including loading, or capturing, material, such as soil, at one location and dumping, or depositing, the material at another location. For example, the scraper portion of the machine may include a bowl within which material may be captured, and a cutting edge located adjacent a cut opening of the bowl. Although various scraper configurations are available, scrapers are often pulled by a tractor, such as a wheeled or track type tractor having a first powertrain for propelling the machine. In addition, scrapers may provide their own traction via a second powertrain that applies rim pull, or power, to the wheels of the scraper. Such machines, including both tractor and scraper powertrains, may be referred to as dual powertrain machines.
During certain operating conditions, such as when the tractor powertrain is in top gear and at or near maximum speed, the scraper powertrain may be capable of pushing the tractor powertrain. To avoid this and other inefficient operating conditions of the tractor scraper, it may be desirable to balance the torque load of the engines of the two powertrains. Additional machines or applications using multiple engines to power a common load may also operate more efficiently where the torque load is balanced, or equally distributed, among the multiple engines of the system or machine. Land well service rigs are one of many additional examples of multiple engines providing a common source of power.
U.S. Pat. No. 4,137,721 to Glennon et al. (hereinafter Glennon) discusses a control system for two gas turbine engines of a helicopter power plant. In particular, the control system adjusts fueling to the gas turbine engines based on speed error signals and a torque feedback. The torque feedback generally includes a difference, if any, between the torque output of each of the engines. For each engine, the speed error and torque feedback are summed and input into proportional and integral control channels. Although Glennon may provide one strategy for controlling plural engines, the torque feedback aspect appears tightly integrated with the fueling control and, thus, may not be readily provided as a retrofit. Further, there is a continuing need for improved control strategies, including torque load control strategies, for multiple engine systems.
The present disclosure is directed to one or more of the problems or issues set forth above.